Sinopec (SNP), China's second-largest oil producer, is vulnerable to China's efforts to tame fuel prices as the country's policymakers work to curb inflation. The government raised tariffs three times last year, by less than 5% each time, and cut once, while average crude prices increased 28% compared with 2009, according to Bloomberg News.

With China's energy demand soaring, Sinopec's refineries were operating at a record pace last month. China is the world's second-largest oil consumer behind the U.S. One research firm said the Chinese government could raise diesel and gasoline by as much as 20% this year to stem consumption.